RT，感觉暴力除了IO优化之外已经优化不了了……

#include<cstring>
#include<cstdio>
using namespace std;
char s[2000000];
unsigned long long ans,l,maxn,nowl,x,mp[200];
int main(){
	scanf("%s%llu",s,&l);
	nowl=strlen(s);
	for(unsigned long long i=0;i<nowl;++i){
		mp[int(s[i])]++;
		if(mp[int(s[i])]>maxn)maxn=mp[int(s[i])];
	}
	x=maxn;
	while(nowl-x+maxn<l){
		maxn=maxn<<1;
		++ans;
	}
	printf("%llu",ans);
	return 0;
}